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What is a Transit?

◊ A transit is when a planet passes directly between the Earth and the Sun

◊ The solar eclipse is when the Moon passes between Earth and Sun and partially to totally blocks out Sun

◊ Venus and Mercury are the only planets between Earth and the Sun so the only ones that can Transit

Solar Eclipse

2004 Transit of Venus

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What is the Transit of Venus?

◊ Venus passes directly between Earth and the Sun during its orbit

◊ Appears as a black disc, or silhouette moving across the Sun

◊ Takes around 6 hours

◊ Path of an upside down “U” because the Sun appears to rotate across sky

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History of Transits

◊ Come in pairs separated by over a century

◊ Earliest recorded in 1639

◊ 1769 Transit observed by Lieutenant James Cook

• Sent by Britain to Tahiti

• Took measurements using traditional Surveying, Mapping & Astronomical principles

• After the Transit he explored & mapped south-east Australia

◊ 1761 and 1769 observations calculated the size of the Solar System applying Kepler’s 3rd law of planetary motion

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Computational analysis

◊ Spherical Trigonometry used to plot & map the Universe

◊ Astronomical Unit (AU) is used to measure the distance from Earth to the Sun

◊ Calculated by measuring how long it takes Venus to transit across the Sun

◊ Two different locations

◊ Measure distance between locations ie Latitude & longitude

◊ Time the contacts 1 & 3

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Observing the Transit - THEN

◊ Historical observations required Surveying and Astronomy skills

◊ Surveyors used stars to help identify positions on the earth

◊ Surveying skills were needed to make maps for navigation and exploration

◊ Most explorers were also Surveyors:

• Captain James Cook

• Matthew Flinders

• Will (from Burke & Wills)

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What is Surveying?

◊ Surveying is the measurement & mapping of the environment

◊ Use specialised tools and equipment

◊ Principles of

• Maths

• Geography

• IT

• Science

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Observing the Transit - NOW

◊ Modern technology now uses Global Positioning Systems (GPS), satellite remote sensing and other space-based measuring techniques.

• Still based on early Surveying, Astronomy and Mathematics principles to fix positions and take measurements.

• Tools are faster, more economical and provide more precise results.

• Specialist field called Spatial Science

You will experience a rare Astronomical event

◊Last transit was in 2004

◊Next Transit will happen in 2117

◊6 June 2012 – the last in your lifetime

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Observing the Transit – 2012

◊ Never look directly at the Sun – serious damage can occur

◊ Safe viewing

• SolarScope

• Webcast

• iPhone App

◊ Using the SolarScope

• Simple but sophisticated tool

• Look inside the SolarScope

• View a large size projection

• Take time measurements

SolarScope

iPhone App

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Observing the Transit – 2012

◊ Never look directly at the Sun – serious damage can occur

◊ Safe viewing

• SolarScope

• Webcast

• iPhone App

◊ Using the Solarscope

• Simple but sophisticated tool

• Look inside the Solarscope

• View a large size projection

SolarScope for safe viewing

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Acknowledgements

◊ Donated on behalf of Surveying and Spatial Science Industry, and Astronomical Association of Queensland

◊ Student education

• about the Transit of Venus

• how Surveying was integral to early Astronomy

• consider career opportunities

◊ More information

• Transit of Venus: www.transitofvenus.com.au

• Surveying: www.alifewithoutlimits.com.au

• Spatial Science: www.destinationspatial.com.au Sources:

• Surveyors & Astronomy & Future (Peter Swan, Bob Ross, Connie Beadell, Graham Tweedie 2012)

• National Aeronautics and Space Administration (NASA)

• Bill Kitson (ABC Radio interview Adelaide Mar 2012)